Arrangement for long-distance reception by means of intermediate receivers



March 5, 1935. M. VON ARDENNE ARRANGEMENT FOR LONG DISTANCE RECEPTION BY MEANS OF INTERMEDIATE RECEIVERS Filed June 24, 1931" 12M ampl fie On uenioi: M M #M Patented Mar. 5, 1935 UNITED STATES PATENT OFFICE ARRANGEMENT FOR LONG-DISTANCE RE- CEPTION'BY MEANS OF INTERMEDIATE RECEIVERS Manfred von Ardenne, Berlin, Germany, assignor to Radioaktiengesellschaft D. S. Loewe, Berlin- Steglitz, Germany, a company of Germany Application June 24, 1931, Serial No. 546,594

In Germany 4 Claims.

proposed to enable the inhabitants of a town to receive the weak signals of distant broadcasting transmitters which, otherwise, would be overlapped by nearer transmitters, especially the local one, and by local disturbances. A receiving station is placed in the surroundings of the town at a point where undisturbed reception is possible. The receiver is connected with an amplifier and the latter by a lamp-loaded free line or cable, if necessary with intermediate repeating amplifiers, to a transmitting station in the town itself, the transmitter being controlled by the last amplifier. As receiver, amplifiers and transmitter are untuned, the transmitter will radiate a practically true copy of the high frequency field at the point of reception so that any receiving station in the town is able to receive a desired far broadcasting station as well or better as if itself would be situated outside of the town.

This system would work well under the condition that in no case, even when the maximum amplitudes of the single carrier waves are coincidental in phase, the linear part of the characteristic of one repeating element (valves) is exceeded. When this condition is not fulfilled, distortion and interfering combination frequencies would be created. On the other hand fulfilling of this condition would mean limitation to a very small part of the characteristic and involve an extremely uneconomical working of the systems.

According to the invention this difficulty is overcome by limiting the range of frequencies repeated by the-system to less than one octave, so that the highest frequency is less than the double of the lowest frequency to be repeated. In this case the first multiple (octave) of the lowest frequency will be already higher than the highest frequency so that no interference can take place. In order to transmit the local range of broadcasting frequencies (200 to 600 m.) consequently two complete rebroadcasting devices, say for 200 to 350 and 350600 m. are required.

The drawing shows diagrammatically how the invention may be carried into practice.

1 is the receiving loop antenna.

2 is a band filter.

B is an untuned amplifier.

4 is the line connecting the receiver to the transmitter.

5 is one of the repeaters inserted in the line.

6 is the end amplifier.

7 is a frequency band filter.

8 is the transmitting antenna.

The antenna 1 is picking up the high frequency field exciting on the point of reception. The loop June 26, 1930 may be so directed as to avoid back-coupling by the energy radiated by antenna 8. The broad band filter 2 lets pass to the amplifier 3 only the frequencies of the range of less than an octave. In the lump-loaded line 4 are inserted repeaters 5 constructed in a well known manner. The end amplifier 6 is furnishing the energy for the non-tuned transmitting antenna 8. The filter 7 of the same characteristic like filter 2, is not absolutely necessary.

Various other modifications and embodiments of the system described above will occur to those skilled in the art, the scope of the invention being defined in the following claims.

I claim: I

1. A system for transmitting by repeating stations, a band of. frequencies comprising a plurality of carrier waves, consisting of a repeating receiver, a repeating transmitter controlled by the frequency band received, valve amplifiers for passing said band during repetition, and means for limiting the band of controlling frequencies so that the maximum controlling frequency is less than twice the lowest controlling frequency.

2. A system for transmitting by repeating stations a band of frequencies comprising a plurality of carrier waves, consisting of a repeating receiver, a repeating transmitter-controlled by the frequency band received, valve amplifiers for passing said band during repetition, and means for limiting the band of controlling frequencies so that the maximum controlling frequency is less than twice the lowest controlling frequency, said means consisting in a band filter in the input of said repeating transmitter.

3. A system for transmitting by repeating stations a band of frequencies comprising a plurality of carrier waves, consisting of a repeating receiver, a repeating transmitter controlled by the frequency band received, valve amplifiers for passing said band during repetition, and means for limiting the band of controlling frequencies so that the maximum controlling frequency is less than twice the lowest controlling frequency, said means consisting in a band filter in the output of said repeating transmitter.

4. A system for transmitting by repeating stations a band of frequencies comprising a plurality of carrier waves, consisting of a repeating receiver, a repeating transmitter controlled by the frequency band received, valve amplifiers for passing said band during repetition, and means for limiting the band of controlling frequencies so that the maximum controlling frequency is less than twice the lowest controlling frequency, said means consisting in band filter in the input and output of said repeating transmitter.

MANFRED VON ARDENNE. 

